Japanese patent application JP 1-66355 discloses a closure cap including a base portion including an internally-threaded skirt for screwing onto the neck of the receptacle, and that is surrounded by an outer covering skirt. A lid is hinged onto the base portion by means of a hinge including a spring-forming tongue that assists the opening movement of the lid. An opening control element can slide over the base portion in order to act on the lid and on the hinge.
Such a cap is not completely satisfactory, in particular from an appearance point of view, since, at rest, when the lid is closed, the opening control element projects forwards by a non-negligible amount.
European patent application EP 0 699 591 discloses a cap including an outer covering skirt that is interrupted on the side remote from the hinge, so as to receive the opening control element which comprises a presser hinged onto the base portion and a presser member that is suitable for sliding in a recess of the base portion. The presser member comprises ramps for co-operating with portions in relief of the lid so as to cause said lid to rise, and an end for acting on the spring-forming tongue of the hinge. The presser member includes an oblong cutout in which a dispenser endpiece is engaged. Such a  cutout is likely to encourage the accumulation of dirt, as is the recess in which the presser member slides.
French patent application FR 2 685 294 discloses a closure cap that functions in a fairly similar way, and that is likely to present the same drawbacks.
U.S. Pat. No. 6,834,769 describes a receptacle including a closure cap in which the opening control element slides inside the base portion. On the side remote from the hinge, the opening control element includes a projecting portion on which the user must press in order to open the lid. The opening control element must be made in the form of a separate part, thereby increasing the cost of manufacture. In addition, the user is provided with an area on which to press that is relatively small, thereby decreasing comfort in use.
European patent application EP 1 281 628 describes a closure cap that is made in a similar way.